Polymorphism of HSP70 gene is not associated with type 1 (insulin-dependent) diabetes mellitus in Japanese.

Heat shock protein (HSP) 70 is one of the stress-induced proteins and a candidate for islet autoantigen of Type 1 (insulin-dependent) diabetes mellitus. Association of PstI-8.5 kb allele of HSP70 gene with Type 1 diabetes was previously reported in the Caucasian population. Since HSP70 gene is located in the class III region of HLA, the association may be due to the linkage disequilibrium between class II HLA and HSP70 genes. To study whether HSP70 gene is associated with Type 1 diabetes independent of class II HLA genes, we analyzed both HSP70 gene and class II HLA genes in 32 Japanese patients with Type 1 diabetes and 31 control subjects. By Southern blot hybridization with restriction enzyme PstI and HSP70 genomic probe, two allelic bands, 9.0 kb and 8.5 kb, were detected as reported in the Caucasian population. The allele frequencies of 8.5 kb in Type 1 diabetic patients and normal controls were 0.39 and 0.44, respectively. There was no significant difference between the two groups. On the other hand, by PCR-RFLP analysis, DQA10301, DQB10303 and DQB10401 alleles were positively associated with Type 1 diabetes and DQA101 was negatively associated with Type 1 diabetes. These data suggest that the polymorphism of HSP70 gene was not associated with Type 1 diabetes in the Japanese population, and that association of PstI-8.5 kb allele with Type 1 diabetes observed in Caucasian population appears to be due to the linkage disequilibrium between this allele and HLA-DR3.